How to View & Clear the Mac NVRAM Contents from Terminal in OS X



advanced Mac customers might also find it vital to view or immediately manage firmware variables found within NVRAM on the laptop. generally the NVRAM incorporates unique system records approximately matters just like the machine audio level, startup disk info, an energetic user name, display screen backlighting and determination, and different technical info. at the same time as most customers haven’t any enterprise interacting with NVRAM, there are instances whilst manually viewing and clearing out NVRAM variables may be beneficial for troubleshooting purposes.

With the assist of a command line device in OS X, Mac users can without delay examine and regulate firmware in OS X without having to reboot the Mac and appearing a standard NVRAM reset.

This in all likelihood is going with out announcing, however apart from listing the nvram contents, users should certainly now not delete or clear nvram variables if they don’t recognise exactly what they’re doing and why.

To get began, release the Terminal, observed in /applications/Utilities/ and issue the following commands, relying in your desired objective:

how to View All NVRAM Contents on present day Mac
trouble the subsequent command to print out all modern-day NVRAM contents:

nvram -xp

this will show the output in XML format, that is a great deal more readable than the default format, that’s read with the -p flag:

nvram -p

if you don’t specify -x flag, you’ll in all likelihood see quite a few gibberish, XML, and possibly a few undeniable text mixed in that is effortlessly readable, however for the most part this statistics is handiest going to be relevant to superior Mac customers for troubleshooting purposes.

An example of nvram -p output may also appear to be the subsequent:

$ nvram -p
efi-apple-payload-data %20%10%00%CC%00U%00P%00D%00A%20%10%00%CC%00U%00P%00D%00A%20%10%00%CC%00U%00P%00D%00A%20%00U%00P%00D%00A00U%00P%00D%00A00U%00P%00D%00A00U%00P%00D%00A00U%00P%00D%00A00U%00P%00D%00A00U%00P%00D%00A00U%00P%00D%00A00U%00P%00D%00A00U%00P%00D%00A00U%00P%00D%00A00U%00P%00D%00A00U%00P%00D%00A00U%00P%00D%00A00U%00P%00D%00A
efi-boot-device IOMatchIOProviderClassIOMediaIOPropertyMatchUUIDBD2CB9D3-8A79-4E2F-94E2-C5EC9FEBBA64BLLastBSDNamedisk0s3%00
SystemAudioVolumeDB %00
prev-lang:kbd en:0

again, this will be meaningless information to most users however advanced Mac users can discover useful information in the NVRAM in the event that they recognise what to look for.

the way to clear All NVRAM from the Command Line in Mac OS X
the next maximum useful trick is to be able to clear out NVRAM with the equal command string. To delete all nvram variables just use the following syntax:

nvram -c

For changes to take effect, you should reboot the Mac, for this reason unless you’re doing some thing else you can want to simply provoke a reboot from the command line at the same time as you’re there.

Deleting specific NVRAM Variables on Mac OS X
To be greater particular, you can additionally goal a set nvram variable for removal with the -d flag:

nvram -d (variable key call is going right here)

as an example, to clear the device audio setting from nvram:

nvram -d SystemAudioVolume

Going similarly with nvram adjustments
The nvram command has other makes use of as well for superior users, from settings like disabling the startup boot chime sound on a Mac to continually booting into verbose mode in OS X or maybe allowing safe boot mode from the terminal for faraway management or a headless/keyboardless Mac. For those inquisitive about getting to know more about this powerful command, the person page for nvram is pretty useful, as is the primary –help flag to reveal other syntax alternatives:

% nvram –help
nvram: (usage: no such option as –)
nvram [-x] [-p] [-f filename] [-d name] [-c] name[=value] …
-x use XML format for printing or reading variables
(must appear before -p or -f)
-p print all firmware variables
-f set firmware variables from a text file
-d delete the named variable
-c delete all variables
name=value set named variable
name print variable
Note that arguments and options are executed in order.

whether or no longer you find this vital or clean simply depends for your skill stage and your wishes. Many superior Mac customers understand they also can reset the PRAM / NVRAM on boot with a key collection, which can be useful in troubleshooting some unique troubles as well, and that approach gets rid of the entirety from NVRAM similar to the -c flag at some stage in an real reboot, that is possibly less complicated for plenty customers to keep in mind. that is especially treasured for running with faraway machines connected thru SSH or discovered some other place at the community, where it might be not possible to manually reset NVRAM with a keyboard shortcut series.

another common instance in which clearing nvram can be useful for troubleshooting purposes is when the Mac App save hundreds a clean show that received’t populate with any content or store statistics. For anything cause, the nvram -c flag and rebooting nearly usually resolves that trouble by myself.



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